1. Field of the Invention
The present invention is directed to a diaphragm spring clutch and more specifically to a two-part pressure plate having spring means interconnecting the parts thereof.
2. Prior Art
It is well known in conventional clutches to construct the clutch disc in such a manner as to achieve gradual clutching, to prevent the generation of vibrations and to obtain smooth engagement. The friction faces of such a clutch disc may be mounted on the disc by means of axially flexible disc springs. Another type of prior disc clutch achieves a similar cushioning effect through the pressure plate rather than the clutch disc. According to this type of clutch the pressure plate is comprised of two plates arranged parallel to each other and to the clutch disc. The two plates are interconnected so as to be axially movable with respect to each other by means of slidable guides provided therebetween and connecting means which limit the movable range. Resilient spring means are provided to move the plates apart from each other and to also impart the desired cushioning effect. However, according to a clutch construction of this type a high degree of accuracy in the manufacturing and assembling of the clutch is required in order for the plates to move smoothly in the axial direction relative to each other on the guide means. Furthermore, sliding resistance is frequently increased due to the accumulation of foreign materials such a the worn powder from the clutch facings on the sliding surfaces of the guide means. Also, the plate located furthest from the clutch disc may not be uniformly retracted due to an irregular operating force of the release lever when the plate does not move smoothly because of a possible disengagement of the plates from the sliding surfaces of the guide means. As a result the cushioning effect is adversely affected resulting in the generation of shock or abnormal vibrations due to sudden torque transmission. Finally, it is difficult to arrange the two plates in coaxial relationship with respect to the rotatable shaft.